Several reason that I'm sure OP could have thought of by himself.
FPS vs Adventure game (just that should be enough)
On top of that it's an FPS from a developer known to be really good at making FPSs
It's much more marketted and it got a huge boost in popularity thanks to E3
inFamous has never been big, fyi inFamous 2 had 160k pre-orders the week of its release. So 250k with 3 weeks less on an much smaller install base isn't something I'd see as a bad thing.








